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Is there a name for aircraft weapon load photos?
I remember as a kid I had a couple of books full of spec sheets and big glossy photos of military planes with every standard piece of weaponry laid out in front of them, something like this (c/o Tech Sgt. Robert Horstman/US Air Force via Business Insider):

Is there a standard (official or unofficial) name for this kind of staged photo?

Welcome to Av.SE!

First idea: static display

Also: https://photo.stackexchange.com/questions/12694/how-do-i-take-pictures-of-planes-flying-at-an-airshow

what about: vanity shot?

I like "grange display", though I imagine that's not in use anywhere

It is rather hard to find if there is a specific name for this sort of photo it appears to be referred to as a weapons Array in this Wikipedia link-(https://en.wikipedia.org/wiki/Aircraft_ordnance)
To see how it refers to the images you will have to look at the sidebar where it has three of these types of images. The top and bottom images are referred to as Weapons Arrays while the middle one refers to it as its Array of Weapons.


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Compute Thrust from RPM and Induced Velocity
I'm attempting to calculate the difference in thrust in a secondary propeller operating in the wake behind a primary propeller, in the context of a trailing quad-copter following a leading quad-copter in close proximity.
I'm using the model from Propeller Slipstream Model for Small Unmanned Aerial
Vehicles and have so far simply linearly superimposed two of the induced velocity fields on top of one another, as far as I am aware a linear superposition should give a reasonably accurate induced velocity field for now.
I'm wondering if there is a way to calculate the thrust a propeller is creating just from this induced velocity field. I should also note that the thrust the propeller generates is one of the input variables into the model, so I am assuming that I will need to work out how much additional thrust the second propeller requires to give the flow field generated

source: Stack Exchange

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Is the Boeing 737 MAX 8 MCAS exceptional in operating when autopilot is off?
To the uneducated reader it seems strange the Boeing 737 MAX 8 MCAS system only operates when autopilot is off. I understand the reasoning behind why it was implemented to operate when autopilot is off. My question is, is the operation of MCAS automated system when autopilot is off an exception for the 737 line, or are there other automated systems providing direct control surface actuator inputs when autopilot is off on the Boeing 737s? If so, what are these?

All large swept-wing aircraft have a yaw damper, which is always active. It takes an input from a yaw gyro and applies rudder inputs in order to counter Dutch roll.

Many aircraft have stick pushers.  These push the stick or yoke forward to prevent a stall and that actuates the elevator nose down.  For example, take a look at the Bombardier Q400 or this FAA AC:

This answer seems almost completely unrelated to the question in its current form.

The 737 Max is not exceptional in operation, in that many aircraft use a stick pusher when the autopilot is off.

A stick pusher is explicitly (and very) different from the MCAS.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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How to calculate the glide distance?
Can somebody please explain how I go about this problem?
A Cessna 172S is flying at 9842.52 ft from the ground and the engines stop producing power.
If the aircraft is in a glide configuration and the best (quickest) rate of descent recommended is 3.4 m/s (800 ft/min) at a speed of 68 KIAS. What is the maximum range that can be reached?

"and the engines" well, engine.  Is this a no-wind situation as well? Head will reduce the range, tail will enhance, crosswind might do either depending on the direction.   Assume no wind. 9842ft/800 ft/min = so many minutes of flying time. Minutes of flying time x 68 knots (1.15 miles/hours) = number of miles you can go. Do the math.

9842.52 feet is bizarrely specific! Oh, wait, that's 3000 meters.

You really want the quickest rate of descent?  I'd expect that is a straight-vertical descent powered by gravity (aka, a nose-dive), with a total glide-distance of about Zero.

"Best rate of descent" is "slowest" not "quickest"

Basic Math:
How long will the plane be in the air?
$\frac{9842.52 ft\ \text{AGL}}{800\ fpm} = 12\ \text{minutes}$

How far will the plane go in 12 minutes?
$68kts \cdot \frac{12\ minutes}{60\ min/hr} = 13\ \text{NM}$
Assumptions

Assuming no tail wind or head wind, so that KIAS relates to actual ground-speed.
Approximating that 68 KIAS is the ground-speed, when it is in fact the slant-distance speed.   If you need a precise answer, apply the Pythagorean Theorem to refine the answer.

@abelenky's answer is correct if you're on the ground and therefore have time to look up figures and do the math.  If you're in the air, the rule of thumb for light aircraft (with a typical glide ratio of 8:1) is 1.5nm per 1,000ft AGL, after subtracting 1,000ft or so for flying a pattern around your landing site.  Rounding 9,842ft to 10,000ft, that gives a gliding range of 9×1.5=13.5nm, which is close enough in an emergency.
Note that the Vg (if any) given in your POH assumes max gross weight; if you're lighter, your best glide speed decreases and your gliding range increases.  And of course, that all assumes no wind, which is unlikely in the real world; you'll generally want to glide downwind (to maximize range) and then do a 180 to land with a headwind, which is covered by the 1000ft subtracted above for the pattern.


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turboprop thrust relative to the jet's propulsion
What is the thrust ratio in a turboprop between propeller and its jet exhaust, and is the jet exhaust necessary for flight? Once the turbines are spinning, it seems the exhaust is waste product. This would be inefficient and could be used for more power. Is this so?


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Why does RPM for a fixed-pitch propeller change with an aircraft's pitch?
Talking bout a C-152 -
If I pitch the aircraft down, and without adjusting the throttle, the RPM would show an increase. Pitch up, and without adjusting the throttle, the RPM shows a decrease.
I've been told that by pitching down you increase the amount of airflow your engine is receiving while pitching up decreases the amount of airflow, or that the propeller at different pitch attitudes either forces more air or acts against the air entering the intake ports, or that it's because of the propeller angle of attack.

Think of it like driving a car up a steep hill.  If you don't step on the gas your car will slow down due to the force of gravity and if you don't add more throttle the engine will follow due to the added drag.

Gravity - it's pulling the aircarft down so it makes the plane faster when pitching down and slower when pitching up

The driving variable here is airspeed, not pitch attitude per se.  Your airplane naturally goes faster when you put the stick forward and decrease the wing's angle-of-attack, and this changes the prop rpm.
Your pitch input is changing the wing's angle-of-attack which leads to an airspeed change.  Even with the engine switched off, the aircraft would fly (glide) at a higher airspeed with the stick forward than with the stick aft.  And for a given throttle position, a fixed-pitch prop turns faster at a high airspeed than at a low airspeed.
Just as a wind turbine does.
Your tachometer can be used as an airspeed indicator.
The key factor is the speed of the air flowing through the propeller disk-- with a fixed-pitch prop, this dwarfs any effect related to the amount of air being forced into the engine.
And yes, this effect can be explained in terms of the angle-of-attack of the propeller blades.  Increasing the airspeed decreases the angle-of-attack of the propeller blades, "unloading" them, or in extreme cases subjecting them to negative loading so that the prop is driving the motor rather than vice versa.
In a fast dive at a low power setting, the wind (airflow) is making the prop move, not the other way around, and you'd pick up more airspeed if the prop fell off.  But even at a lower airspeed and higher power setting, the speed of the oncoming airflow has big influence on the speed of the prop's rotation.

Having the prop fall off in a dive is a great way of picking up airspeed! Unfortunately, there are drawbacks in other areas of the flight, so it's not a recommended technique.

Because airspeed influences the effective angle of attack of your propeller blades.
Consider what happens when you move this propeller from a stable cruise condition to a dive. In a dive, the incoming airstream increases, so a propeller with a fixed geometric pitch will have a smaller effective angle of attack. It will then generate less lift and drag, and thus need less torque to rotate.
Consider this paint.exe marvel:

An increasing forward speed component tends to align the airflow with the propeller blade, reducing its angle of attack.
Since the rpm of the propeller-engine combination is stabilized where the torque output of the engine equals the torque requirement of the propeller, the rpm will increase to the new equilibrium.

Because your hydrostatic load changed
The RPM changed instantly because the hydrostatic load on your prop changed.  Because air is a fluid. Effectively, your prop is a fluid coupling.
An example of "not a fluid" is an engine geared to cogs on a rack railway.  An RPM change must match a speed change.  Not here.
Compare to your car's automatic transmission torque converter- the most common fluid coupling in normal life.  It intentionally has "slip" so the engine can idle at 600 rpm while the car is stopped.  This slip varies by engine force: if you push the accelerator, the engine will rev more while still stopped. On a slight downhill, it slips less, and on a steep downhill, it can actually push (windmill??) the engine*.
There is a relationship between throttle position, engine RPM, and hydrostatic load (resistance).
Your propeller is the engine side of a torque converter.
When you pitch down, you change induced drag, i.e. the airflow is resisting less.  You have instantly removed hydrostatic load from the prop, so the engine RPM instantly increases.
Put it another way, at any given altitude, weight, pitch and throttle position, the airplane will seek to "balance out" at a particular RPM and airspeed.  But it won't get there instantly. You can change pitch angle very quickly, but it takes awhile for airspeed to change.
So in that moment when you have pitched down and you have not gained airspeed, the air is resisting less (because the airplane wants to go downward on its own, like going down a hill on a bike)... so the RPM must increase.
Again, air is not a rack railway.

* however you can't "windmill" start an automatic transmission car. That's because the gears are engaged hydraulically by a pump on the engine side...

Comments are not for extended discussion; this conversation has been moved to chat.


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Difference between constant speed and variable pitch propellers?
Here is how I currently understand constant speed and variable pitch propellers.
In constant speed propellers, the pilot controls the governor via the prop control knob and the speeder spring, flyweights, and other parts of the system act accordingly to increase or decrease the amount of oil entering the propeller hub. This automatically changes the blade pitch in order to maintain a certain engine RPM, even in an over speeding or under speeding condition. Setting the engine at 2300 RPM will keep the engine at 2300 RPM at all phases of flight even if no adjustments to the blue knob are made.
In a variable pitch propeller, the pilot adjusts the pitch via the prop control knob for different phases of flight. However, the blade pitch doesn't automatically change in order to maintain a certain engine RPM. The pilot would need to adjust the prop control in under speeding or over speeding conditions. Setting the engine at 2300 RPM will not keep it at 2300 RPM if climb or descents are made without adjustments to the blue knob.

Is my understanding of both kinds of propellers correct?
Are the flyweights only found in constant speed propellers? Are there any other parts in the system that can only be found in constant speed propellers and vice versa?

Your understanding is essentially correct.  A constant speed prop is governed.  A variable pitch prop is not.
Constant speed props are also variable pitch.
A constant speed prop will only maintain speed if there is sufficient power from the powerplant.
Most constant speed props will require slight tweaking to maintain the rotational speed during a flight.
Constant speed props require a governor, and the flyweights are a component of a governor.

Can you give an example of an aircraft that uses a non- constant speed, variable pitch propellor?

The Beechcraft I discussed above.

I think some DC3s used variables pitch, not CS, props.  The Beech electric prop is another example.  It's controlled with a tiny knob similar to the panel lighting knobs.

I flew a DC-3 back in the mid-70's which had a variable pitch prop, but it had an STC, and I believe that the DC-3 normally came with a constant speed prop.

@mongo - what was the benefit of the STC?  Just curious.

The STC was for a powerplant and propeller combination, which was not the powerplant the DC-3 was initially certificated for. Later we got turbine powerplants and the turboprop upgrade was a new STC.


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Can I use the load factor to estimate the lift?
If I have a fixed aircraft as the baseline, then I am not sure the specific flight condition, can I use the load factor to estimate the lift on the wing?

Besides, I can have access to the mass and the mass distribution of the wing.

If you know where the CG is, and where the aerodynamic centers of the wing and the tail are (I am assuming a traditional configuration) so you know the distance from the aero center of the wing to the CG = d_wing, and similar for the tail, and you know the moment the wing generates (ignore the moment about the tail...it is small), and you know the load factor, then you can figure out the total lift generated by the wing. You have two equations:
Sum of moments about CG = 0 (constant pitch rate)
d_wing x liftWing + d_tail x liftTail + wingMoment = 0

Sum of lifts equals load factor times weight of aircraft
liftWing + liftTail = loadFactor x weight

Now solve for liftWing.

If you mean total lift force, then yes you can as Lift = Load Factor * Aircraft Weight.

The lift you get from that includes the lift from the fuselage and the tailplane. And it is a vector sum so yes the tailplane does matter.

That’s what I meant by total lifting force.

Do you mean the load factor that I get from the handbook is the total load factor not just the load factor for the wing?

@CarloFelicione Yes, the reason I commented is because the question spoke about lift of the wing.  But you can discuss that with Allen.

@CarloFelicione Could you tell me how to get the load factor for the wing?


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Why are the AOA sensors placed outside the aircraft?
Why should the AOA sensors be placed outside the aircraft? Is it not the angle between the chord line of a wing and a vector representing the relative motion between the aircraft and the surrounding air, in which case, is it not possible to measure the AOA with a simple instrument inside the cockpit, which eliminates malfunction due to exposure?

If you feel the several hundred knots relative wind of the aircraft inside the cockpit you have bigger problems than wear & tear of AoA sensors due to exposure.

How would you measure “the relative motion between the aircraft and the surrounding air”?

Please everyone: answers in the answer field, not the comments

Questioner starts from the wrong premise, because he does not know what the AoA sensor does. It is unfortunate that the question was closed as unclear. Related: https://aviation.stackexchange.com/q/2317/17780

I've reopened the question. Having a wrong premise does not prevent answering, I think that it actually make it easier, just address the wrong premise.

No, it is not possible to place the sensors inside the aircraft, because the angle-of attack sensors need exposure to the surrounding air, in order to measure, as you mention yourself, "relative motion between the aircraft and the surrounding air".

This is not totally correct there are software only angle of attack systems out there.

@Dave but that's an estimate, not a measurement.

To my knowledge, no one has invented the method to measure the outside flow from inside. This doesn't mean it can't be done, as one could imagine, for example, an array of sensors using some kind of doppler velocimetry or other techniques to determine velocity and flow direction. It would likely be finicky, and in my experience standard AOA indicators are robust (it blows me away that the 737 has had multiple sensor failures).

There are a few "software only" AOA solutions out there like the one offered by Aspen that do not involve any sensors (aside from the regular pitot system).

Since Aspen's Evolution AOA indicator calculates angle of attack from
  the flight envelope data received from the air data computer and
  attitude heading reference system (AHRS) integrated in the Evolution
  1000 PFD or Evolution 1000 MFD, and a certified GPS it does not
  require additional hardware, nor does it require any external aircraft
  modifications or sensors

And its even FAA certified but as others have noted its only an "estimate".
But to truly measure angle of attack you need information on the fluid through which you are moving

is the angle between a reference line on a body (often the chord line
  of an airfoil) and the vector representing the relative motion between
  the body and the fluid through which it is moving

it is true that you need some sort of direct knowledge about the relative airflow to make an accurate measurement of the AOA. But the amount of equipment needed outside the fuselage can be minor
Check out Dynon avionics solution for an AOA sensor
The AOA logic is internal to the fuselage, and no moving parts (e.g. wind vane) are mounted  outside.
however this, like any other Pitot tube will have known issues with icing.


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Can a drone be seen on TCAS?
On condition that the pilot reports to ATC, an aircraft's TCAS sees a drone in the vicinity.
How can the pilot be sure that it was a drone on TCAS? What kind of symbol is shown on TCAS that can be identified as a drone? Or is it just a primary radar target pick up by TCAS?

Are you asking about big drones like the predator or small, multi rotor drones?

Do you have any reason to think that a pilot would ever make such a report?

No, a drone will normally not be visible on an aircraft TCAS. The TCAS system is based entirely on direct communication between aircraft transponders, so both parties (aircraft and drone) must have a transponder in order for TCAS to work. Normal drones do not have transponders, so they will not be visible on TCAS.
If a pilot reports a drone near the aircraft, what he means is that he (visually) has seen a drone out the window, not that it is indicated on an instrument anywhere. Besides, TCAS does not know different aircraft types, so even if a drone had a transponder and it was presented on a TCAS, the pilot would have no way of knowing that it was a drone (as opposed to any other aircraft).

Or just primary radar target pick up by TCAS.

TCAS is NOT a radar. It is not able to display anything without a transponder. And even ground based primary radars will not necessarily pick up a small drone.

"he has seen a drone" - believes that he has seen a drone

@ChrisCharles - He has seen something which is believed to be a drone.

@J... no - he may not have seen anything at all - it may have been an optical illusion, reflection or a moment of insanity.  If you wanted to highlight that maybe the pilot could be reporting without believing there was a drone then that would be fair - the pilot could be reporting it because of some other motive - but your correction is wrong.

@UKMonkey All of those things (illusion, reflection, insanity) are "seeing something".  If a pilot reports a drone, we can be quite certain that the pilot saw something.  We have variable certainty that the thing is a drone.  In any case, I was being deliberately pedantic to point out the ridiculousness of being overly pedantic on this issue.

@J... I believe part of UKMonkey's point is that if we're going to that level of pedantry, there's no reason to believe the pilot saw anything at all. Perhaps they are reporting a drone because they're a jerk and want to mess with people...

@mbrig Because pilots, ATC... all a bunch of clowns, really, especially at work. ;)

@J...  +mbrig exactly - I was pointing out that if you're going to be a pedant then get it right... if someone has to correct your correction, then it's better to say nothing at all.  Also - insanity doesn't mean they've seen something - it just means that they're making the call while not of right mind.  That might include seeing things, but then it might not.

TCAS is based on aircraft transponders, so unless the drone has one installed it cannot be seen by TCAS.
At least no commercial drones intended for consumers have transponders installed. On the other hand drones are not allowed in airspaces used by airliners so there should not be a need for one.

... unless they have ATC approval, though I don't know how often that is given.


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Can a VFR flight follow an IFR route?
Can a VFR flight follow the same route of an approved IFR route (such as those found on Forefight Route Adviser) using waypoints and Victor airways?

With the exception that the VFR flight should be at intervals of 500 feet (eg, 7,500ft, 8,500ft, etc), while IFR flights should be at intervals of 1000 feet (eg. 7,000ft, 8000ft)

Yes.  In fact, before GPS came along, if you were flying somewhere and wanted to use your VOR to get from A to B, that's exactly what you did a lot of the time if it was convenient; fly along the victor airways if they were more or less on your route.  IFR traffic is only separated from other IFR traffic and when VFR in non positive control airspace you can go wherever you want notwithstanding other restrictions.
In the GPS era nobody uses VORs very much any more and you can fly direct almost all the time when VFR (I haven't used the VOR in my plane in eons; mostly I just use a tablet or my phone), but there is nothing to stop you from flying along an airway if you feel like it.

If you are in airspace that requires a clearance, it requires a clearance and you fly where you're told. If you're in class E that requires no clearance, you can fly on the airway or across it or whatever. If you are out on a sightseeing trip, just meandering about, you may cross all sorts of airways.  IFR traffic is only separated from other IFR traffic.  An IFR flight in VFR conditions still has to look out for VFR traffic although ATC will help them out as much as possible.  This only really happens with GA IFR flights below 10000 ft where you have IFR and VFR GA traffic operating together.

For low altitude flights ie below FL180, yes you can.  You can use either Victor (VOR) or Tango (RNAV) airways.  You will fly at VFR altitudes during cruise, but use of these airways on VFR flights is common.  For improved safety and traffic separation, pilots are requested to either file and open a VFR flight plan or request flight following when VFR on Victor or Tango airways, especially near navaids or other high density airspace.
Victor and Tango Airways can also be used for VFR flight segments during composite flight plans like VFR on top, VFR over the top, etc.

When filing a VFR flight plan with an ATS route identifier in it, consider the following:
- check that the aircraft is equipped with suitable navigation aid receivers (e.g., ADF, VOR, GPS)
- check the lowest altitude permitted for that specific ATS route
- make sure the weather / clouds will allow you to climb and maintain the minimum ATS route altitude in VMC at all times
- make sure to use VFR altitudes (xx500) , not IFR altitudes (xx000), as mentioned above already
- specify the point, where you plan to join and leave the ATS route.
If something doesn't match, you can still fly the same direction and use the same navaids, but don't specify the ATS route in your flight plan. Instead, you can specify point along the ATS route with maximm 30 min flight time intervals.

I’m not familiar with the term 'ATS route'. Could you specify which country this applies to?

@JScarry ATS routes is an ICAO term and thus applies worldwide. Definition: „An ATS route is a specified route designed for channeling the flow of traffic as necessary for the provision of air traffic services. It is used to mean variously, airway, advisory route, controlled or uncontrolled route, arrival or departure route, etc.” Source: ICAO doc 4444-PANS ATM


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Could a C-130 Hercules be built using WW2 technology?
I'm looking at this as a "time traveller carrying only designs in his head" scenario.
Obviously turboprop engines are out of the question, but how close in capability would it be possible to get a C-130-style aircraft for use by June 1944 if our hypothetical time traveller arrived at Boeing or Lockheed in September 1939, and was able to prove his bona fides and be put to work with adequate resourcing?

He'd have probably been more useful to get them started on the B-29 or P-51 in 1939. Or the X-1!

It's possible to get something in the vicinity of the C130 during WW2. The C130's predecessor, the Fairchild C123 'Provider', was powered with two WW2 era P&W R2800 radial engines, each producing 2000 hp. Presumably, the design and number of engines could have been scaled up.
Remember that a defining characteristic of the C130 isn't it's payload, it is the rough field landing capability, which includes STOL. I've been in a C130 when it was practicing short field landing and takeoff, and the experience was... dramatic. When it hit the runway, it really did hit the runway... with a bang.
A piston powered transport with somewhat the same capabilities of the C130 was produced in the 1950's, the Blackburn Beverley, used by the RAF. The Beverley was built with WW2 technology, and was powered by WW2 vintage Bristol Hercules and Centarus radial piston engines.
The Beverley was abandoned in favor of the turboprop Armstrong Whitworth Argosy, or 'Whistling Tit' in RAF parlance, when it became available, just as use of the C123 was phased out as the C130 became available in sufficient numbers. The greater power and substantially lower maintenance requirements of turboprops made them the logical choice when they became available.
Given that the C130 was initially produced with Allison T58 turboprops, at 3500shp, a four R2800 C130 would have had a power deficit. The larger P&W R4360 at 3000 hp could be used, although it was still having development problems during the war.
A WW2 vintage C130 would have had longer takeoff and landing, and a lower payload, due to the lower power available and the heavier weight of the power plants, but it was possible with the technology of that day.
Would it have been produced? Given that WW2 had its own unique requirements, probably not. Aircraft production was centered around warplanes and transports with long range, such as the Douglas C54. By the end of the war, the Allies had prepared field construction down to a fine art and the teams in place to build those fields quickly in both theaters, so the need for a large transport with rough field capability wasn't as evident.
Where the C130 really became valuable is in lower intensity conflicts that followed WW2, where expert runway construction teams aren't available on short notice, and the front lines of combat aren't nearly as well defined.
So, to a degree, the changing nature of armed conflict defined the need for the C130.

The spelling of the Blackburn plane is "Beverley". The RAF Argosy AW.660 variant was nicknamed the "Whistling Tit" by RAF personnel, for reasons that should be clear if you look at a picture. The British European Airways civilian AW.650 variant was the "Whistling Wheelbarrow".

No hyphen in Armstrong Whitworth.

The question is unbounded, the answer really depends on how much of the manufacturing supply chain the time traveler intends to upgrade. The time traveler is in a sense taking the technology back in time with him so anything could be built at any point in history if the knowledge base is broad enough. Is the design of a turbo prop engine not part of the C-130 design?

Wonder if the Navy/Marines would have been interested, especially if it could get off a carrier.  They did have much larger distances to cover for re-supply.

Launching is conceivable, they used B-25s  for the Dolittle raid. Can it take the stress of landing on a carrier is totally different though, the B25s were one way and landed in china. Add a steam catapult or booster rockets(jato bottles) to be sure. Of course the navy already had long range flying boats as an option, first crossing the Atlantic in 1919 and culminating in the Hughes H-4 Hercules. (spruce goose, and just a bit too late for the war) Ships just carry several order of magnitude more cargo and for less fuel and other costs.

Apologies again for the lack of clarity in my original question, perhaps it could have been be better stated as "Why did it take so long to come up with a military cargo aircraft using the airframe layout of the C130?"


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What is the longest period of time an aircraft type has been grounded due to safety concerns?
Obviously inspired by the current 737 Max situation, what is the longest period of time that any individual type of airliner has been grounded for safety concerns (excluding those that never returned to service)?

I think that the de Havilland Comet was permanently removed from service after catastrophic pressurization failures. https://en.wikipedia.org/wiki/De_Havilland_Comet

@JScarry: Not quite - several military Comet 1s were rebuilt with stronger fuselages and returned to service (although none of the commercial ones), and the Comet returned to commercial passenger service in 1958 with the Comet 4, which had the bad luck that the bigger, more capable 707 entered service just a few weeks later.

@Sean If you rebuild them, does it count as the same aircraft :)

@JScarry: According to the regulators, it does.

Possibly of interest: https://news.aviation-safety.net/2019/03/14/list-of-global-aircraft-groundings-in-history/

The Yak-42 was grounded from June 1982 to October 1984 (26 months) for a cause similar to Alaska Airlines Flight 261.

After the crash of Air France 4590 (July 2000), the Concorde was grounded until November 2001 (same link) - 16 months.

The Yak-42 was grounded for roughly 2 years due to stabiliser malfunction.
The de Havilland Comet was grounded for OVER 4 Years (Aug 1954 - Sept 1958)
because of blown out windows, causing decompression and in-flight disintegration.

Space Shuttle was grounded after Columbia crash from 2003 February till July 4, 2006 with only single test mission over this time in 2005.
Columbia crashed while flying at Mach 19.5 (23,278 Km/hr; 14,464 Mph), at 209,800 feet altitude (63.9 km; 39.73 mi). It is probably possible to argue that at the time of crash it was flying as an aircraft (glider), interacting heavily with the air, and it disintegrated because of aerodynamic forces.

Ah, but I did specifically say airliner in the body of the question. Still worth including of course

Depends on the definition of the airliner. If just "intended for carrying multiple passengers or cargo in commercial service" as Wikipedia says, Shuttle might qualify. It is at least quite big and expensive.

The Space Shuttle was grounded for 36 months following the Challenger disaster and again for 29 months after the loss of Columbia.
Whether that qualifies as an aircraft or as a falling brick is debatable, though.

The Boeing 787 was grounded from January 17, 2013 to April 26, 2013 due to lithium ion battery problems.  I think this may be the longest a commercial airliner has been grounded but I am not sure if there is a military plane that was grounded for longer.

technically it wasn't grounded. The AD stated it was required to undergo specific modifications before being allowed to fly, modifications which weren't available at the time. But there was no AD forbidding the operation of the aircraft.


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Why do airline schedules start in March and October?
Is there any specific reason as to why airline schedules for the summer season start around 27 March and winter season around 27 October? Thanks.

Why are people voting to close this as off-topic? This is about airline operation.

The main reason for new schedules in March and October is the Daylight Savings Time changeover.
It is a MAJOR headache for airlines all over the world. Schedules have to undergo extensive restructuring during the switch over from summer daylight savings time to winter standard time. Maintaining code-share connection times is the biggest priority.
What makes this all very difficult is the fact that many countries and localities do not observe daylight savings time, or have different dates for the switch-over. This is especially true for flights between northern and southern hemispheres.

During Nov-Mar, snow is common in Europe and the continental US, which means (a) more schedule padding to account for airport delays and deicing, and (b) passengers wanting to fly to ski destinations.
During Apr-Oct, snow is unusual in Europe and the continental US, which means (a) less schedule padding due to good weather, and (b) passengers wanting to fly to beach destinations.
Airlines flying in other regions probably have different scheduling periods to account for different weather trends, e.g. summer/winter reversal in the southern hemisphere, monsoons near the equator, etc.

since the question does not specify, there is a specific reason why you restricted the answer to the continental US? (also, took me a while to figure out that acronym, can we skip them, if not really needed?)

The dates/seasons fit the northern temperate region, excluding oceanic islands.  I'll add Europe since I now realize that fits too, and their carriers seem to switch about the same time as the US ones.

It may also be worth to note that many airlines nowadays codeshare - thus synchronized time table changes are a plus.


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Does/Can combustion instabilities occur in SCRAM jet?
I was told that combustion occurs at Supersonic speeds in SCRAM jet. So acoustic disturbances/ pressure fluctuations can't travel into incoming jet stream. Does this avoids combustion instabilities in SCRAM jets?

SCRAMjet literally means Supersonic Combustion RAMjet, so the first part of your question is not in any doubt.

I don't understand your question. "So acoustic disturbances/pressure fluctuations can't travel into incoming jet stream." Is that a statement, a question, and what does it mean because I'm afraid it doesn't make sense.

@GdD, yes this sentence ("acoustic disturbances/pressure fluctuations can't travel into incoming jet stream") is the statement I'm making. Based upon that I have this question "Does this avoids combustion instabilities in SCRAM jets?".

@GdD: Subsonic instabilities can be caused by resonance - pressure waves affecting combustion and causing said pressure waves, amplifying them. If combustion happens in supersonic flow, there is no way for those pressure waves to travel forward, so resonance would not be possible.


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Using ANR aviation headset with a PC
I just started my studies towards PPL, and am looking into buying a good ANR aviation headset for flying on Cessna 172.
I have an office job, and I'm dealing with a lot of noise, hence ideally I'd like to use this headset with my computer as well (as buying 2 ANR headsets for different purposes is quite an expense).
From what I understand aviation headsets normally have 2 jacks with a different diameter. There are probably adapters to convert them to a standard 3.5 mm jack, but I wonder if it affects its noise reduction capabilities.
Conversely, can I buy a PC-compatible headset, and use it for flying with an appropriate adapter?
Also, most ANR headsets seem to operate on AA batteries. Are there any with lithium-ion battery instead, so that it can be recharged?

You can use rechargeable batteries in aviation headsets without any issues.

@JScarry the only issue I heard of (and I'm not sure if it's true) is that at some point the batteries might appear fully charged, but will only have like 30% capacity, and would fail you during the flight

@jFrenetic If that is an issue (I don't know), then it would be trivial to work around by using a different set of batteries while flying. Just add "headset - flight batteries installed, verified" to your own checklist of things to do or grab before going to the airport. (Since you'll be moving the headset around, you'll need some way to remember to bring that, anyway.) You can also look at the headset specs to see what the audio isolation is without the ANR; any credible manufacturer should have that bit of information readily available.

@jFrenetic As aCVn7 says, some headset brands are better than others when noise cancelling is turned off but none of them lose their basic ability to hear and talk. In any case, after a couple of lessons you should be able to fly the plane and  swap out batteries at the same time.

The answer to all of our questions is broadly yes, but to break it down:
This company makes mic's for the Bose ANR audio headsets (quiet comfort line) that may fit your use case.
You should be able to use a step up adapter to plug any standard aviation headset into 3.5 mm. It might be worth noting that many of the headsets out there now have bluetooth that you can bus audio through including the mic audio for talking on the phone. However its worth mentioning that most aviation ANR headsets are bulkier than your typical ANR headphone as they also offer passive isolation should the batteries die.
AA batteries are the chosen option as they can be easily sourced just about anywhere and quickly replaced. Some people may chose to use rechargeable ones. I would think the lack of battery options has more to do with the fact that for a situation beyond regular old batteries many people may opt for the panel power variants.
FWIW the audio quality (for music) is decent but not headphone quality on my zulu 3 as most aviation headsets are designed to work well in the voice range and not necessarily the full frequency spectrum range that a set of headphones will work well in.

Thanks a lot! So, the first option you mentioned would be applicable to an existing PC headset? I imagine all aviation headsets come with a mic? (especially at such a price)

@jFrenetic it is applicable to only the QuietComfort models they list, its not a general solution for all ANR headsets out there as it seems to be custom fit to the headset input on the Bose units. And yes all aviation headsets (as far as I know) have mic's

A headset, by definition, combines headphones and a microphone, no? If it doesn't have a microphone, it's just a set of headphones; possibly with passive or active noise reduction, but still just headphones.

@aCVn It depends who you ask, generally, r.e. aviation thats true but more broadly speaking the term "headset" may be used to apply only to headphones or even over ear plugs if the application does not dictate a mic being attached.

Here's a site comparing many of the headsets that are available
https://www.sportys.com/pilotshop/aviation-headsets/guide.html
I don't know if laptops support audio-out via bluetooth (I've not seen that, my HP Probook and my Lenovo W530 don't), so you might want to look at units which accept a wired Aux-in, and then plug in a wire from the laptop  headset jack to the unit's Aux-in.


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What are the STOL features on the Pilatus PC-6 Porter?
What's so special about the Pilatus PC-6 Porter that makes it a world-leading STOL aircraft? How do its features work?

Quite simple.  Big wings with decent flaps, lots of power.
11.2 lb/hp at gross.  Wing loading of 19 lb/sf.
Comes down to how slow can you fly, and how fast you can get to that speed.  Without exotic high lift devices, it's mostly about wing loading and power loading.  The Pilatus only has to accelerate to a little over 60 mph and there is power to get it there in around 600 feet.  So there you go.
It's STOL, but not what I would call "super STOL".  For that you'd need full span flaps and slats and or bigger wings and a higher power to weight.  Like a Helio Stallion.
The Porter isn't a unique super-plane and it doesn't have any fancy high lift secrets.  It still needs about an 800 ft runway.  It just has a good all around configuration for its job, easy to load, and is simple and rugged.  It's the simple and rugged + good-enough-for-most-short-strips short field performance that's made it successful.

Don't forget the prop beta range which allows to reverse the prop in flight for very steep approaches.

Although it is done, use of ground beta mode - discing or even reversing props in flight- is a big no-no and is not something you could use to promote the airplane performance wise.  DeHavilland Canada pilots used to do that on Twin Otter demos but after some crashes in the 70s they were told to stop or else.  I'd be surprised at any operator that lets their pilots use less then flight idle until on the ground.

Are there any other really good STOL planes?

Pretty much everything DeHavilland Canada designed between the Chipmunk and Dash 8, DHC 2 thru 7 https://en.wikipedia.org/wiki/De_Havilland_Canada.  The DHC5 Buffalo was 49000lbs and could operate from a football field.  The notable design feature for DHC products was full span double slotted flaps.  They dispensed with LE slats because you have to operate at crazy high pitch angles to exploit the STOL benefits of slats.  DH Canada was the US Army's go-to supplier of STOL utility airplanes up to the mid 60s.


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Why the need for the MCAS on the Boeing 737 Max 8?
Was there a problem with stalling on 737 jets before the 737 Max, if not then why is MCAS needed on the 737 Max 8.If it was a problem why did Boeing wait so long.


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Basic question regarding flight levels
Dear fellas I'm building a program to simulate flight plans, for academic purposes and, I have read a lot about flight levels and specifications but I need to be absolutely sure of what I am doing.
The reading that I have made always mentions the circular rule:
    Eastbound – Magnetic track 000 to 179° – odd thousands (FL 250, 270, etc.)
    Westbound – Magnetic track 180 to 359° – even thousands (FL 260, 280, etc.)
I couldn't find any examples when flying in the opposite direction (179° to 000 ) neither any mention to flight level change when crossing from from westbound to eastbound (359° to 45) , reason for which I'm quite confused.
I got the data regarding the airports (lat, long) from https://openflights.org/data.html
They mention that for Longitude: Negative is West, positive is East, e.g. CDG (Paris) 2.549, FRA (Frankfurt) 8.570, LIS (Lisbon) -9.135
So my questions are:
1) if I am flying from LIS to FRA is it a westboung flight fom LIS until longitude 0, and then it becomes an eastbound flight from longitude 0 to FRA?
2) based on the previous question, the flight plan should consider taking off from LIS climb until to an even flight level e.g. FL380, cruise at FL380 until the aircraft reaches longitude 0 and change the cruise flight level to an odd flight level eg FL390?
I would really appreciate your help (I am not a pilot, I'm doing a PhD in Operations Research)
Francis

LIS is west of FRA, therefore generally the flight is eastbound.

East and West does not flip at longitude 0....

As you said the rule is based on the magnetic track of the flight, how is that related to crossing longitude 0?

So part of your question is what happens if the plane is actually flying westbound but the magnetic track is between 000 and 179 degrees? Find a student pilot to sit down w/ you and get you straightened out, it will be good for you both.

The special case is actually flying in the polar region where magnetic compasses become useless. Look up grid navigation.

Your mistake is in thinking that geographic Longitude 0 and the longitude + and - values east or west of Longitude 0 are a factor in all this.
It's a lot simpler than that.  It's even FLs on any track west of north/south on any longitude anywhere, and vice versa.  In other words, even heading for the sunset, odd heading for the sunrise, anywhere on earth.
So Lisbon to Frankfurt being a north easterly direction, it's odd, and you would file an odd FL in your Flight Plan.
It's a convention.  What happens in practice though is that the FL you're assigned is often a couple of levels above or below, and while it usually sticks to the convention, it may not always, especially if close to a N/S track or the track will flip through north or south and change from westerly to easterly as a result, because it curves around for some reason, or some other expediency, and a controller my clear you to an odd FL even though you are technically going westbound, or vice versa.  But anyway...
Another complication: the track requirements usually change from magnetic to true when in the higher latitudes, depending on the local airspace designations, generally north of 60 to 70 deg.

"Westbound" does not mean "currently located on westerly line of longitude".  It means "going westward".  The track of the flight as drawn on the earth's surface is progressing toward the west.

A plane flying direct from LIS (LPPT) to FRA (EDDF) will follow a magnetic track of 045.  Since 045 is between 000 and 179, it is "eastbound" and should therefore use an odd flight level.  It's really that simple.
The convention of west longitude and south latitude being negative is just to allow storing coordinates in computer databases as two signed numbers, i.e. without separate direction flags.  It has nothing to do with the above rule, which predates computers.


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Hover Performance in Helicopter dynamics
What do we mean by “good” hover performance in Rotor dynamics?
If I want to analyse hover performance of a helicopter, then What parameters should I monitor?

You may want to check out the "figure of merit."  It's not perfect, but is a useful metric of hover performance.  A figure of merit of 0.8 is considered good according to some sources.
Figure of merit is defined as the ratio of ideal hover power (for a given thrust T, air density $\rho$ and rotor area A) to actual power required (P), i.e.
$$ F = \frac{  T \sqrt{ \frac{T}{2 \rho A} }}{P} $$
F=1 indicates that a rotor is perfectly efficient; it operates at ideal power.  If the real power is larger—the rotor is less efficient—the figure of merit decreases.
Since real, practical rotors have blades with drag, nonuniform inflow, etc they will have F<1.  An efficient rotor could have F as high as 0.8.
For a given helicopter, F can change based on the flight condition.  For example, when hovering closer to the ground—in ground effect (IGE)—F will be larger/better.  Also, F may increase with gross weight (more passengers, cargo).  This is because thrust will increase to counter the added weight, which means blades operate at larger angle of attack, typically with larger lift to drag ratio (L/D).
A common mistake people make with F is to associate high values with good helicopter design.  There are reasons why low F can be better.  First, a helicopter with a larger rotor and smaller F can require less power than a helicopter with a smaller rotor and higher F (at the same thrust).  This is because F won't give you bonus points for the larger rotor, it's already factored out that advantage.
Also, a high F rotor may be less capable of high speed flight, maneuverability or other desirable characteristics.  A rotor may have low F because other design goals were more important, e.g. max speed.
For more information here are some slides by Prof. Sankar (see slide 45 ~20min).  There's also a good discussion in this article on helicopter performance.


text:
Humidity and its effect
We know that humidity degrades engine performance. Is there any charts or tables which quantify effect on engine performance due humidity?
The question is specific to helicopters.

Figure 11 in GE Gas Turbine Performance Characteristics estimates the impact of humidity on some of their turbine engines.  It shows a power loss of less than 1% over a large range of humidity.
Additionally, I've read that the effect of humidity on helicopter turboshaft engine performance is negligible.  This was in flight manuals for specific helicopters, which I unfortunately can't share here.  What I can say is that these manuals provide charts specifying the maximum power or torque available at various air temperatures and pressures.  For humidity, however, they tell you to ignore it.
This article on helicopter engines also indicates that humidity effects are small compared to temperature and pressure.


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Helicopter tail horizontal stabilizer angle
In helicopters what factors decide the horizontal tail stabilizer angle?
By angle I mean that in some helicopter they are -6 deg relative to tail boom while in some -3 deg.
These angle were remain fixed although provision is there to change the angle.

The stab angle influences the pitch attitude in cruise, allowing the body of the machine to be flatter (more nose up) than it would be without it, by pushing down on the tail with speed.  It also dampens pitch oscillations of the body under the rotor disc.  A designer will come up with a stab area and incidence that is estimated to provide the necessary down force for a desirable cruise attitude for a particular machine, then adjust as required during flight testing.
The Blackhawk takes it much farther; the stab is a moveable control surface that allows attitude control over a very wide speed range.

Would you consider upvoting a question that you've supplied an answer for?


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Why is CL/Cd equal to L/d?
I'm making a school project where I intend to design and calculate an rc airplane. Reading some books I found something I can't understand, it says that CL/Cd is equal to L/d, but the only possible way to make that true is to use the same surface on Drag and Lift equations. Isn't drag equation supposed to use frontal surface and Lift equation to use wing surface?

The frontal surface is indeed used for the drag coefficient of cars.
For airplanes, however, almost* all coefficients use the wing area as their reference. This makes sense exactly because it allows to express L/D as c$_L$/c$_D$.
* For the nitpickers: Control surface hinge moment coefficients use the area of their respective control surface, not the wing surface.

Thank you Peter, I was really struggling with that one, because the Cl/Cd made sense but using the frontal area would make the L/d absurd.

Your answer makes me wonder something, If the area is constant at any AoA (wing Area), wouldn't the parasite drag coefficient need to change at different AoAs? because I'm "showing" more or less area to the relative wing which should increase drag

@LucasDelgado The area you "show" to the flow is only relevant in super- and hypersonic flow. Since subsonic flow bends around the plane, it is the length of the flow path that matters, not the area facing the flow.

Ok that makes sense, I have only one more question, I'm sorry if it sounds stupid, why resistance goes up when slipping in a plane of frontal area doesn't matter?

@LucasDelgado: Haha, good point. Now we are leaving linear aerodynamics and the blunt fuselage at an angle doesn't behave like a wing but more like a barn door. Similar to cars, now the frontal area does have some bearing on drag.

I'm really grateful for your answers, they were of great help!!


text:
What is this aircraft doing?
I spotted this aircraft on FlightRadar24 flying a strange route. What is it doing?

Does this answer your question? Why did this aircraft fly in this pattern over Southern Italy?

Looks like it's flying to me.

http://bioflight.dk/ says they do "digital surveys" and "visual surveys."  The precisely parallel and equally spaced passes better visible here suggest the former (camera images, stitched together after landing), not the latter (a human observer).


text:
Where is pure outside static air pressure indication on A320?
I'm looking for the indication of the outside static air pressure in the cockpit.
Where is it located? One of the ECAM pages?
Thanks!

What is your reason to believe it should be displayed as anything else than pressure altitude?

My incompetence in avionic... Is the static pressure used somewhere else as in pressure altitude? For some other calculations that are not displayed?

Airspeed measurement requires static pressure (dynamic pressure is total pressure, in pitot probe, minus static pressure), but the usual approach is to measure the difference directly (though I don't know whether A320 ADIRU does that). And then there are some altitude-dependent limits in the flight laws. Also the transponder transmits pressure, ignoring the baro setting.

Maybe one of the computers with displays shows for maintenance purposes raw static pressure value? So the technician can check pressure against some value in the ground test equipment?

I doubt practical test equipment would show anything else than pressure altitude to be directly compared with the altimeter. That way it can be used with any altimeter and the point of the test is to check the altimeter reading anyway.


text:
When should I request clearance to return to altitude, after leaving cruise altitude?
I can not understand the term”cruise” perfectly.
I know I should request ATC clearance to return to cruise altitude, if I leave cruise altitude to out side of the block.
Ex) Cleared cruise altitude 6000, MEA is 4000. The block is between 4000 to 6000. So I can descent or climb within the block without clearance. if I leave to out of block, i need ATC clearance for return to the block altitude
There are two which I am confused.
First, Can I descent/climb several times without clearance within the block or just once is possible?
Second, When I leave assigned within the block, still should I request an

Your question is incomplete, it says "still should I request an".

The “cruise” terminology you are questioning is really not used anymore. It still appears in manuals, but it was very confusing and fallen out of use. The intention of a “cruise” clearance was to allow the pilot to climb or descend as required with the specific cruise altitude window. In your question that was 4000’-6000’. However, today people the same request would be made as “request an altitude block 4000-6000”. ATC would respond “(callsign) is cleared the block 4000 to 6000.” No further calls are required from you while maneuvering in that altitude block.
Sometimes a “cruise climb” clearance will be issued to heavy aircraft to allow them to climb slowly and level off for a while when they are too heavy to climb all the way to their final altitude. In that case they can climb as they are able but are not allowed to descend out of an altitude they have already climbed to.

Thanks, sir! Your examples are really helpful for me to understand.


text:
How far would a landing Airbus A380 go until it stops with no brakes?
If an Airbus A380 lands with all brakes disbled, including reverse thrust, wheel brakes and any other measures it has to stop or slow down. Then how long would it take it to reach a complete stop.

How is a question that could literally be answered by providing an equation possibly be considered for closing as "primarily opinion-based"?

If someone had a flight simulator, he could see how much does the speed decrease over a certain distance and then we could extrapolate when does it reach zero.

Flaps, drooping ailerons, spoilers do contribute to slow down, so is it in clean configuration? Or not?Should it be in full configuration, what landing speed?  Do you understand  how unprecise is this question? Why not asking a question such as : To slow down  what is the relative effectiveness of the brakes, ground spoilers, reversers ...compared to each other?

This sounds like a Blues Brothers quote: "OK, it's a hundred and six miles to Chicago, we're in an A380, we've got no brakes, no thrust reversers, it's dark, and we're wearing sunglasses". "Check". "Hit it!"

Into the EMAS, through the EMAS, through the fence, into the bay, out of the bay and into the nightclub district.  At least they'll have margaritas...

OP: The answer depends directly on how well trimmed the grass is at the end of the runway, and where the next building is. For any arbitrary location in the populated areas of the Earth, that A380 will roll right into whatever is after the runway unless the grass is really overgrown, like rainforest overgrown.

@dotancohen length of grass is probably irrelevant, the wheels are going to sink into the mud regardless of grass length.

@user40476 it’s not unreasonable for answer to make a few assumptions like minimum landing speed for a clean configuration. Yes it’s not a precise question but that doesn’t mean an estimate can’t be calculated.

This is a very hypothetical question. If the aircraft has no means to slow down it has to lose all kinetic energy through rolling friction and air resistance. Both of these are very small (and get smaller as the aircraft gets slower) and will not have too much effect on a heavy aircraft like the A380 with an enormous amount of kinetic energy. Therefore the aircraft will continue to roll way beyond any runway or proper landing surface.
For high speeds, the air resistance will have the bigger impact on slowing down the aircraft (air resistance is about proportional to the square of the true air speed). Once the aircraft gets slow, the air resistance gets very little and rolling friction (highly dependant on ground surface) will be the bigger force to slow down the aircraft.

I bet it stops a lot faster once it overruns the runway and the ground below its wheels gives way.

It depends
In practice, it would keep on rolling (as TomMcW summarises it) "until it hits something". It will run into something before it stops of its own accord.
How far it would roll if there were nothing in the way depends on a lot of things, some of which are discussed below.
Real-life or idealised conditions?
Are you asking about an idealised perfectly smooth and level runway, in conditions of still air? Or are you asking about real-life conditions?
I'm assuming that your disabled measures include the flaps, so now the plane is coming in for an over-speed landing.
Real-life runways are not long enough; under most conditions your plane would run off the end, onto rougher terrain.
Also, real-life runways are also often inclined. Once something like an A340 is moving slowly, its enormous mass needs only the slightest encouragement to keep rolling indefinitely to overcome friction.
Perhaps the closest we can get to an idealised runway is a desert salt flat, but the weight of a landing airliner would probably be high enough to damage it substantially and have a very rough experience.
Then we have to decide: how much fuel, how many passengers (i.e. how much mass has to slow down)? What's the air density? Will the tyre fuses blow because of overheating due to the prolonged high-speed roll?
Too many variables
In short, too many variables, and adjusting just some of those within real-life limits could change the stopping distance by an order of magnitude.
Calculating with an idealised model
A different way of asking the question would be to agree on the weight of the plane at landing (passengers plus fuel).
Then, we decide that it is landing at its minimum possible speed without flaps (180 knots, perhaps).
Now we have its momentum.
It's going to land on a perfectly flat smooth runway, in still air, at STP (standard temperature and pressure: 0 degrees C, 1 atmosphere). The runway has no end.
At that speed, air resistance will help slow it down. An engineer will be able to calculate the aerodynamic drag under those conditions, but there'll be quite a bit at first, and it will drop off rapidly as the plane slows.
We'll assume the tyres miraculously remain inflated until the plane comes to a complete halt. An engineer, again, will be able to calculate the friction of the wheels and tyres.
Our engineer will be able to combine the drag and friction into a calculation that includes the initial mass and landing speed to give us a curve that finally reaches zero.
Under these perfect conditions, the plane will roll for many kilometres. The tail of the curve will be shallow and very long.

tl;dr: Until it hits something.

Hmm. Why should the tires burst?  Moving and load will rise their temperature, but not fast and much. The car tires for a Porsche or Ferrari of class (Y) can hold more than 300 km/h. Of course this is a huge plane, but we neither apply brakes or plan to turn around.

Tyres burst all the time!

I'd expect the tires to enjoy this trip - the roughest thing they experience is touchdown, and then it's a cool, gentle rollout with the kinetic energy providing them a cooling breeze, instead of being converted into heat in the brakes. If they survive touchdown, they should hold.

If the lack of braking is all known beforehand, crew should assess the survivability of a runway excursion on wheels at substantial speed against that of a wheels-up landing. I bet the latter, while much worse deceleration-wise than braked wheel on asphalt, provides more braking action than free-wheeling down a flat runway...

Damage from landing on a salt runway? The Space Shuttle landed on dry lakebeds 60 times. Do the tire contact patches of airliners exert greater force on the landing strip than Space Shuttle tires?

@DanieleProcida - that link shows around one tire incident per day, but there are around 100,000 scheduled flights worldwide each day (44,000 in the USA alone), so based on that, it seems that aircraft tires rarely burst.

Miracle applied ;)

authors: Bob Jarvis - Слава Україні


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Are tiltrotor planes less safe than conventional propellor planes?
I got interested in Tiltrotor type of airplanes and was reading up about some specific models, the AgustaWestland AW609 and the Bell Boeing V-22 Osprey. Both planes have a history of quite a few crashes.
That's where my question comes from: Are tiltrotor planes generally less safe than conventional propellor planes of similar size?

The Osprey had some horrendous development and early service problems but is turning out to be statistically safer than an equivalent helicopter as it's maturing.  But compared to a fixed wing propeller driven airplane definitely less safe from a technical perspective.  Just way more things to go wrong.

You are going to need a definition of safe before this can have a good answer.

John K's comment addresses the Osprey well. For the AW609: well, it's not on the market yet and all problems so far have been during test flights, which are supposed to find the limits of the aircraft. How do you find the limits? Well, you do ever more crazy stuff until the aircraft starts to do crazy stuff. And then you know where the limit is, i.e. you have to cross the limit to find it. There is a reason test flights are performed by specially trained test pilots, who often wear parachutes, and sometimes the test aircraft are even equipped with special escape systems. They do crash.

Also, note that according to Wikipedia's list of tilt rotors, only 19 have ever flown and 12 of those are classified as experimental or testbed. 4 are UAVs. So, there are only 3 tilt rotor aircraft which are not either experimental or UAVs (which generally have different tradeoffs than passenger or cargo aircraft), leaving a total of 3 tilt rotors that have actually flown of which only 1 is already in active service. That is a lot less experience than we have with fixed-wing fixed-propulsion aircraft.

@JohnK Makes sense. And it is a good point to compare it with helicopters as well.

@JörgWMittag Thanks for the details. I didn’t pay enough attention to the fact the the crashes happened mainly during testing. And yes, I understand there’s way less experience with tiltrotors.

This question is opinion based, which is why I voted to close.


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Question about CDI/OBS and HI
Could somebody please explain me the differences between using the OBS and the Heading Indicator? As much as I could understand, once you tune into the VOR, the OBS starts to show how much deflection/ deviation is there. You then turn the OBS to align the needle which shows the direction (in terms of angles) that you need to fly to reach that VOR.
Does this mean that the OBS is the instrument to derive the direction, and serves no direct purpose in terms of heading? I.e. the Heading Indicator is the one that then should align be flying in that new direction, right?

Could somebody please explain me the differences between using the OBS and the Heading Indicator

They are two very different instruments. The OBS is used to track inbound/outbound from a VOR station, whereas the HI (or, DI - Direction Indicator) shows the current direction of travel (assuming it has been aligned correctly with a compass).
"Turning the OBS to align the needle" is not really the usual way to use that instrument * - you set the OBS to the radial you intend to fly, and use the needle to align yourself with that radial.
If OBS and DI agree with the needle centred, you're on the radial selected by the OBS.
* There is of course a use-case where you just want to go direct to a VOR, and then you may just turn the OBS until it shows "TO" with a centred needle. But if you're doing this regularly you might be using it wrong.

Hello!
Thanks! But apologies, I am still confused.
I was watching some YouTube videos, and when tuning into a VOR, the CDI shows To with the needle all the way to the right/ or left. The presenter then turns the OBS knob to align the CDI needle to the centre. That's what I am confused. With that needle pointing straight up (north) it makes it seem that the CDI/ OBS and the heading indicators are all aligned. So, how/ when does one decide to turn?

Another use case is determining where you are with respect to that VOR. Especially when the VOR is equipped with a DME, this will immediately give you your current location.

@Ben You decide to set the OBS when you know you intend to fly along a radial - from your flight plan probably.


text:
Distance to the runway/ touchdown point
Trying to learn about aviation, and looking through all the displays in the cockpit, and also the Garmin G1000,  I am not sure where I see the distance to the runway touchdown point, or the start of the runway. Sure, I see the ILS glidescope indicator, telling me I am too high/low, but where is the runway?
Ergo, my question is this: If flying in heavy fog, dark night, let's say visibility down to 2 meters! how does the pilot know where to land? Some indication of the distance would be great.
Thanks a lot, much appreciated.

While distance to runway would be nice to see, isn’t an equivalent measure (provided you’re on glideslope) the altitude which should be readily available?

The three parameters (height, horizontal distance to touchdown point, glideslope) are linked. Get 2 of them and you can deduce the other one. Once on glideslope, you will touch the runway at the desired touchdown point.

"Ergo, my question is this: If flying in heavy fog, dark night, let's say visibility down to 2 meters! how does the pilot know where to land?" They don't land. There is something called a "decision height" where if you cross that height without visual identification of the runway, you are required to go-around. There are no 0/0 (0 visibility) landing systems in use today (although they exist) and certainly none for light GA aircraft. The ones that do exist for commercial airliners are a type of autopilot so the pilot would not do anything but wait for the bump.

There is no distance to the touchdown point because there isn't a set touchdown point. there's no runway start distance because that's not what you are aiming for. The purpose of the ILS is to get you close enough to the runway to complete a landing visually. If the visibility is so bad you cannot see the runway even when you are right on top of it then you need an airplane with a completely automated landing system to legally shoot the approach.
What you do have a DIS (Distance) reading in nautical miles to the ILS at the top of the screen, which usually tells you all you need to know. This distance is what you use in the approach procedure which you get from the approach plate for the runway and category of approach you are doing. If you get to the missed approach point, which is a set distance from the ILS, without seeing the runway lights then you must go around.
I'm going to assume you are working with a simulator like x-plane or MFS, in which case you aren't bound by procedure, and you can give it a try without endangering anyone. The ILS in most airports is placed right next to the runway, about where you'd want to aim a touchdown, so in a white out condition you would follow it down as far as you can until you contact the ground. It's been successfully done in emergencies, there's a good deal of pucker factor involved.

A touchpoint is defined in UAV landings and ILS landings.

With visibility of 2 meters you cannot land an airplane. Cat IIIb allows no decision height and auto land the plane to touch down point. Even in Cat IIIb, the highest class available, you still need 150 feet of runway visual range in order to perform a safe roll out. When Cat IIIc is available you may perform your 2 meters visibility landing.
Until then your only option is to divert to another airport.
Related : How can landing in zero visibility be safe?

Thank you vasin1987. But is there any reading/ indication, that tells how far you are from the airport/ runway?
Or how does a pilot know when to lower altitudes on the approach (for discussion sake assuming it is a straight line to the runway for even 30 miles?

@Ben https://en.wikipedia.org/wiki/Distance_measuring_equipment Tells you the distance from navaids which usually colocate in the airport. For height above runway you can try radar altimeter.

@bogl i suggest that could be a good new question about mandatory equipment. I have no knowledge about this but I know of no Cat IIIc in operation.

Found it on https://en.wikipedia.org/wiki/Instrument_landing_system: "CAT I relies only on altimeter indications for decision height, whereas CAT II and CAT III approaches use radar altimeter (RA) to determine decision height."


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Upon landing (uncontrolled field), can I exit the runway via a crossing runway?
I understand at a controlled airfield it's a no no unless directed by atc to do so.

Welcome to aviation.SE! Which country or regulations are you asking about?

If you are at an uncontrolled field you are responsible for maintaining situational awareness of other traffic and using UNICOM/CTAF to broadcast your intentions, find out if anyone else is going to be using the crossing runway, look both ways before crossing and then cross.

What Juan said is 100% accurate.  However, in reality, radio communication at uncontrolled airfields is not required, so do not rely completely on that.  Many weekend pilots with older aircraft may not have radios so you have to be very alert, head on a swivel, and make sure there is no traffic heading your way.  In particular, ag pilot and skydive pilots both act like the airport and airspace surrounding it are their private domain, and some of them never, ever look around to see if there's any traffic.  They proceed as if they are the only ones there, the only ones who have full rights to the airspace and runways.  I say all this from actual experience, and several near misses.  No, not all are like that, but many are so you really have to be extra careful at all uncontrolled airfields.  Do not depend solely on radio comms.

This is a very good point. I think the key is to act in a predictable way. So always join via left hand traffic pattern, land in headwind and don’t exit via the crossing runway. Also get familiar with local regulations for exceptions such as right hand traffic circuits. Make your best effort to conform into other traffic for best safety.


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From RAF fighter pilot to commercial pilot
I’d like to become an RAF fighter pilot for many reasons but to become a commercial pilot once I leave the RAF is not one of them. I am, however, curious to know, if I were to become an RAF pilot and served the mandatory service length (12 years) would I be able to then transition into a commercial pilot? How easy would this transition be? What steps would be involved (rough outline)? Would I need to attend a flight school as if I had no flying experience?
Any answers would be appreciated!

I assume you want this in context of an EASA license? Or are you looking for FAA? For the FAA, you would have to go through CPL/ATPL training and obtain those certifications, but you can credit most of your flying experience towards your required hours to obtain the ATPL and Instrument Rating, depending on what you are flying in the RAF.


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What would be the ideal plane specs that minimizes consumption for 1000 kg of cargo payload (slow speed, wing span, whatever..)?
Speaking of electric planes, I wonder what'd be the optimal specs if the only variable that we'd try to optimize was consumption (assuming a 1000 kg payload and 600 mile legs, unrestricted runway)?

Welcome to Aviation Stack Exchange! I did my best to answer your question, but it's a broad topic you are asking about. I think you'd get better answers if you asked more specifically how parts of a plane affect flight performance.

The most fuel-efficient configuration would be one having a very high L/D. The best examples are modern sailplanes, aerodynamically clean, and with very long, slender wings.

To truly answer this question you would have to outline all the theories of aerospace engineering and explain how they interact with each other.
Everything on an aircraft is a trading game, you want more speed, you're probably going to have an aircraft that's hard to control at low speeds since the control surfaces can't be very large when facing extreme wind speeds..
However there are only 4 basic forces of flight. Thrust, Lift, Drag, and Weight. All the crazy designs we come up with in aviation is us trying to manipulate those 4 forces in a way that fits the desired results.
In almost all cases the idea is to maximize Thrust & Lift while reducing Drag and Weight.
You've already kind of locked in "Weight" at 1000KG. However 2 things also add to the weight. The structural weight of the aircraft, and the counter lift weight the real tail wing produces.
So our best airplane would be made out of some super space material that is as light as possible to avoid adding structural weight.
Also on most planes the tail wing produces downward force to stabilize the aircraft and provide stall recovery. However this isn't a requirement, with modern computers powering on the fly adjustments people have made flying wings.
This is really the best aerodynamic shape we have at maximizing lift/thrust ratios. The longer the span of a wing, the more efficient it is.
So basically your plane would be made out of space age composites, have a wing span as long as physically possible and a computer powered control system to keep it all aerodynamically stable without a tailwing.


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Aviation Embedded Systems
I would like to understand the design philosophies of aviation embedded systems that provide real time control and instrumentation like EICAS/FMS/GPWS & TCAS.

What kind of embedded OS platforms do they use? VxWorks Linux, RT Linux
etc..?
Is there a specific design philosophy in Computer Science that is used for ensuring real time behavior? (Just like fault tolerant hardware for fail proofing?)

Hi and welcome! Please consider whether question might be better suited for the Computer Science SE or a similar one. While related to aviation, the gist is about software architecture, which is not the main topic here.

Possible duplicate of What type of computers are in a flight system?

Voting to leave open. It is a question about the specifics of aviation related computer systems, which differ from your generic Windows desktop. Question 2. makes it not a duplicate.

I think this question is about aviation and deserves to remain. It’s not just about piloting. Otherwise things like N1/N2 blades, drags, VOR frequencies etc... all become technical quickly and automatically disqualified

There are various standards out there and ways of doing things but DO-178C is the latest iteration of the document that outlines how real time avionics are to be programed. Certifying agencies like the FAA may have their own supplements/orders that specify specifics for a given jurisdiction, for example here is the FAA's order.
Avionics themselves often connect over the ARNIC data bus.
Many avionics and aircraft companies design their own OS's when they needed them for real time applications

Honeywell, for example, created the digital "engine" operating system
  (DEOS) and Rockwell Collins, the virtual machine operating system
  (VMOS), which it engineered from an earlier LynuxWorks product in the
  late 1990s. Collins licensed the changes back to LynuxWorks in the
  2002-2003 time frame, and LynuxWorks now offers the new version of the
  software as LynxOS-178.

WindRiver did the OS for the dreamliner

Smiths Aerospace chose Wind River Systems' VxWorks 653 RTOS for the
  B787's common core system (CCS), a cabinet that will host 80 to 100
  applications, including Honeywell's FMS and health management software
  and Collins' crew alerting and display management software.

There is a great podcast on designing spacecraft software (basically the same use case) that you can find here.

Its worth noting that the cost to certify avionics tends to be quite high (under the FAA) so code and methodology dont change all to much. Once avionics get certified companies have a way of continuing to make them for a very, very, very long time.


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Are lhe old King KX170B Nav/Com radios monaural?
If so, does this mean I need to use an adaptor to play the output on stereo headphones?  My Stereo-Mono switch does not produce a two-ear audio.  Would this be solved with a converter? Would be nice to receive other pilots and ATC in both ears.

Yes. The idea of listening to anything more than scratchy AM radio via your ADF was an alien concept in the 70s, unless you had some custom system made up for you.  It's really only taken off since ANR headsets have made it quiet enough within the earcups to make music worth listening to.
You just need to get a mono-to-stereo jack adapter to hear the mono signal in both ears.

Wouldn't it be cool if we could hear the other side from the actual direction relative to the own position? Just kidding/dreaming. Never mind.

Thank you very much, John.  Your information might save me hundreds of dollars and hours going to an avionics shop.  I'll let you know.


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Will the plane take off?
First, I was unsure where to ask, here on on Physics SE. Second, I have a strong feeling it might have been asked already somewhere but I didn't find it - so if it was, please link as a duplicate.
Classic "plane on a treadmill"
Suppose we have an aircraft standing on a runway and it turns on engines in an attempt to take off. But that's a special runway - it acts like a treadmill moving backwards at the same speed as the aircraft is going forward (dynamically adjusting that speed if necessary).

What I did is I looked through the web on a classic "plane on a treadmill" problem. One of the best hit is xkcd which kind of states .. "yes" and then goes into different options explaining that "there is no plausible way we could build the treadmill matching its speed to the aircraft" (or did I get it wrong?)
Let's suppose we could
That is - regardless of whether it's possible or not to build such a runway, for the purpose of theoretical exercise let's just take is as granted - we have such a runway.
Will the plane still take off? What will happen?

Planes move relative to the air, not the ground. The engines drive air, not wheels, so you can't build a treadmill like that. The only thing this will do is add drag to the wheels, the aircraft will still move forward and take off.

Cool! Looks like physics SE has the answer I needed after all. Thanks!

If you want the opposite effect, here is an aircraft taking off from a trailer which is effectively a stationary ground under it regardless of how fast the airplane moves in the air.

It looks like neither the physics se question nor the duplicate or near-duplicate on av se will accept new answers- so we need to keep this open!

If by "it acts like a treadmill moving backwards at the same speed as the aircraft is going forward (dynamically adjusting that speed if necessary)", we mean that the treadmill is moving backwards at the same speed as we'd register on a speedometer attached to the wheels of the plane in the manner of a speedometer on a car, then no, the plane cannot take off.  In this case, groundspeed as seen by an outside observer disregarding the treadmill must be zero, so airspeed will not normally be sufficient for takeoff.  See my answer for more.

All the treadmill does is increase the RPM of the tires at rotation.  Airliner tires are generally spinning at somewhere around 800-1000 rpm at, say, 140 kt depending on the diameter.  If the treadmill is running at 140 kt in the opposite direction, the tire would have to be spinning at double whatever it is normally when the airplane achieves liftoff speed.
The question becomes:

Can the airplane's thrust overcome the tire's increased rolling, bearing and brake drag (from casual brushing contact of the brake pads) friction when spinning at double its normal RPM?
Can the tire survive running at double RPM, well above its speed rating, without blowing up?

For:

Probably yes, but it would extend the takeoff distance quite a bit, but...
I would say probably not.  An airliner tire will have a speed rating that has a good margin above the normal operating speed, in the low 200 kt range, with probably some fudge factor above that. So it could probably survive up to, say 230 kt.  Taking it to double its normal operating speed, an RPM equivalent to 280-300 kt, is probably too much and there is a pretty good chance at least one of them would blow up.  Almost certainly if they were recaps, which most airliner tires are.

+1 for first sentence. There really is nothing more than that.

Well yeah, but the 1st sentence doesn't answer the question does it.

yes, it does. Because if the only effect the treadmill has is of turning the wheels, it won't stop the plane from moving and then from flying. And the first sentence does it while avoiding all the problematic issues of wheel friction and runway speed of light limit. Basically, it is the hammer that forces the OP to clarify how exactly does their hypothetical treadmill work. If they need a boundary layer of moving air over the treadmill, then they now have to state it instead of having an ill-defined problem.

But then I would've had comments complaining about the lack of flesh in the answer. I see a no-win no-win situation here lol.

It depends on exactly how the question is phrased and interpreted.
If you phrase the question so that the treadmill speed is constantly adjusted to eliminate any forward motion of the plane as seen by an outside observer, then you are also requiring that the plane's acceleration must be zero as seen by an outside observer.  This means that you are requiring that the plane's wheels spin fast enough to create a drag force (due to tire rolling resistance and wheel bearing friction) equal to engine thrust, even though they are mounted on the axles on low-friction bearings.  That treadmill would have to spin awfully fast to stop the plane from moving forward!
So if we say that "the treadmill turns as fast as the wheels are turning", which is another way of saying "the treadmill moves as fast as the airplane is moving relative to the treadmill", then we are specifying zero ground speed as seen by an outside observer, and the plane can't take off, unless it is extremely windy.  But as noted above, this would involve no ordinary treadmill.  It might have to spin at thousands of miles per hour to create sufficient drag to counteract thrust!
On the other hand, in the question above, we read:

"it acts like a treadmill moving backwards at the same speed as the
  aircraft is going forward"

The key question here is: "going forward relative to what reference frame"?
Taken literally, the most plausible interpretation of the language above is that the speed of the treadmill is equal in magnitude (and opposite in direction) to the groundspeed of the plane as seen by an outside observer.   Now we are no longer requiring that the groundspeed of the plane be zero.  In fact, we are requiring that the groundspeed of the plane NOT be zero, unless the treadmill is stationary.  And we're also requiring that the plane's wheels spin twice as fast as usual at the moment of takeoff.  In which the case the plane will probably be able to take off just fine.
(Another answer notes, likely correctly, that many airliner tires might not tolerate double the normal rotation speed; many light plane tires likely would.)
Note that if we modified the language of the question to reference the "speed" displayed on a speedometer connected to the wheels-- not something we normally find on an airplane!-- then we are back to the first interpretation given above, and the plane cannot take off or even move forward at all.
It's also worth noting that if the engine power were actually applied directly to the wheels, the moving conveyor belt would greatly limit the thrust available for a given total power output, and we'd no longer need to spin the belt at a such a ridiculously extreme speed in order to stop the vehicle from moving forward.  The belt speed would still have to be well above the vehicle's normal top speed, since aerodynamic drag is not a factor- assuming that the moving belt isn't dragging enough air with it to create a significant headwind!
ALTERNATIVE ANSWER -- as the belt spins at the very high rate of speed required by the first interpretation above, it will "drag the air with it" and create a built-in headwind.  The resulting air drag will reduce the total belt speed needed to stop the plane from moving forward.  In fact the built-in headwind just might be strong enough to allow the aircraft to take off after all, with zero groundspeed!  In this case things will get a bit "interesting" as the plane tries to climb up through the wind gradient!
(All other versions of this question appear to not be accepting new answers, and may not actually be exact duplicates.)

Could modify to "SOME light plane tires likely could".

Exactly, except I believe in this formulation it's not necessary that we assume the wheels spin fast enough to create a drag force that equals to engine thrust. The problem statement only stipulates the speeds are balanced, but it doesn't say how. So maybe it's in vacuum or there is no fuel or the plane is fixed by a chain to the ground or the wheels are glued to the belt etc.

Well let’s think about it:
If the treadmill moves at the same speed that the plane moves forward, there is no reason that the airplane cannot begin a takeoff roll and gain enough speed to become airborne.  The reason being is that nobody specified how fast the TIRES on the airplane turn during the takeoff roll.  As such the aircraft is still unrestricted to move forward under its own thrust and accelerate down the length of the runway relative to an observer not standing on the runway surface.
Now if the tangential speed of the tires cannot be faster than the belt speed of the treadmill/runway, the no forward motion of the jet occurs relative to an observer on an independent body.
And incidentally if the treadmill/runway only move at the ground speed of the jet (I presume this means relative to an independent observer) and the tires cannot turn at a speed producing a tangential velocity greater than the speed the belt moves, no motion occurs and the airplane remains motionless.
This meme keeps resurfacing and argued about constantly, mostly by people who 1) Don’t know a whole lot about airplanes and flying not to mention physics 2) fall into logical fallacies for failing to thoroughly read and understand the problem description.  Here’s a detailed discussion.
http://c-aviation.net/plane-conveyor-belt-explained-debunked/


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Topics for high school chemistry project (IB Chemistry IA)?
I have to do an IB Chemistry IA and I wanted to relate it somehow to aviation; however, I can't do anything super complicated though because I'm only a high schooler. Here are some possible topics along with research questions...

Fuels - comparing qualities, response to different variables/environments
Aluminum alloys - strength testing, response to different weather, idk
Antifreeze - how it works, how to strengthen, etc
Paint - UV radiation corrosion, high temperatures

This list could go on and on, but I'm curious what you all think is a good idea. All a topic really needs is just a chemical reaction(s) that can be extensively studied and extended. Also it's important to note I don't actually have to do any experimentation, I just have to find information online in papers and databases. Sorry if these ideas sound ridiculous/outlandish, this is my first time attempting to tackle aviation from a scientific perspective. Thanks for any help.

Hydraulic fluid might be good topic. Plain oil is a fire hazard, where a leak might cause a flammable mist. The phosphate esthers used nowadays are not flammable, but very corrosive.

This is not a discussion forum neither a "make my homework" place. You should define your topic by yourself, make some research and then when you have a question fitting the topic as defined in the help center, come back with your question.

I have to agree with the other reasons for placing this on hold, but you already have some great ideas.  Just pick one and run with it!  Good luck, and check back in if you come up with a specific question tied to aviation.

I'd do aluminum corrosion. Long term, it's the number one lurking monster in any airline's back closet.
There is interesting chemistry, not just in oxidation processes, but how the different alloy compounds used in making the aluminum have different effects on corrosion susceptibility. For example, the alloy 2024 has copper in it, which makes it its own battery and it corrodes readily in moisture, so it is normally supplied with a pure aluminum coating as a protective layer (alclad).
Besides 2024, 7075 is the most common alloy in commercial aviation and has zinc, which makes it corrosion resistant, but it's resistance to fatigue cracking is not so good.
The alloy 6061 has silicon in it which makes it inherently corrosion resistant and you can weld it, but it's not as stiff or strong as 2024.  6061 is popular with homebuilt aircraft because it's cheaper and easier to form.
Then you have the issues of placing aluminum adjacent to other materials.  Aluminum isn't super happy being next to stainless steel (like using stainless hardware against bare alumimum in a moist environment - this is a big problem with sailboat masts) and really doesn't like being next to carbon fibre (on a jet design I was involved with, the floor beams were made of aluminum with carbon honeycomb floor panels and an inadequate barrier between them - it was a disaster in service and the rotted out beams had to be replaced with titanium ones).
Hard to beat as a topic with chemistry and a bit of drama potential to spice up your paper (corrosion is a very painful experience for an airplane owner).  I'd title it "Aluminum Oxide Never Sleeps".  If the teacher is old enough, he/she will get the gag.

Good suggestion.


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Converting lat long & altitude into a line of sight target?
I want to design a long-range ADS-B receiver with a directional antenna (like a Yagi), but in order to maximize its range, I'll need to orient the antenna towards a target (plane) based on existing data from external sources like FR24. I can easily find latitude longitude and altitude data for planes, but how do I convert these values into polar and azimuth angles that I can orient my antenna towards? Essentially, I need to calculate the line of sight my antenna needs to point at in order to make contact with the plane with the antenna's main radiation lobe. Does anyone know I could go about doing this?

I'm puzzled. FR24 use a network of ADS-B receivers around the world to gather most of their data. If you're proposing to use their data to orient your antenna, what do you hope to get that isn't already available from FR24?

This isn't a question about aviation. It's about electrical and software engineering for which more appropriate Stack sites exist. VTC.

I don't understand why you'd want to use a directional antenna with a directionless technology. If you know it's there already why would you need data from it? ADS-B is about what you don't know is there.

Here's javascript source code with a detailed explanation, too long to paste into a standalone answer, but by the time this goes offline certainly a dozen more will appear if they haven't already.
https://github.com/cosinekitty/geocalc/blob/master/compass.html
Online calculator for the same:
https://doncross.net/geocalc/compass.html


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How did pilots avoid thunderstorms and related weather before “reliable” airborne weather radar was introduced on airliners?
How did airline and or mail pilots avoid hazardous weather especially at night before airborne weather radar systems were in use?

They looked out the window!
If you are talking about a developing thunderstorm, especially during the day, they can be quite easy to see in front of you provided decent visibility. Here is some good footage of what it looks like to fly around a towering cell, you will note its fairly easy to see. At night, lightning, even in the clouds tends to be a prominent effect and is a good indicator of "dont fly there". Here is a good picture of that effect (as well as a little story about flying around it).
Of course, summer haze, the dark of a moonless night, shifty weather, or just plain old mistakes sometimes lands planes right where they should not be sometimes with disastrous results.
Here is an interesting report on thunderstorms and aircrafts from 1948 that may have some interesting info for you.

Spectacular pictures, but it seems to me that you're speaking from experience flying pressurized planes at nice high altitudes.  Weren't things different for unpressurized DC-3s back in the old days?  Especially at night?

@rclocher3 my experience comes from flying a Piper Archer at 3000-9000 ft. You can see the storms nicely from that altitude as well, generally head on....

@Dave: Likewise with a Cherokee flying at 10-12K ft,  At night, it's quite easy to see lightning from storms well east of Reno when you're over the Sacramento valley/Sierra foothills.

Your link to noaa.gov is broken.

I´ll second John K´s recommendation of Fate is the Hunter for a first hand account of flying in the 30s and 40s. The style can be a bit too laden in floritures, trying to lend a certain mystique to flying that still existed when it was published, but the content is sound and if you want a glimpse into the aviation world of that era, it is a great read.
To summarize some of the main points:

Reports of winds aloft were reports of the local conditions relayed by radio from aircrews flying in the area of operations and served to inform following pilots.
Experience handed down orally by more senior airmen that were familiar with a particular route.
The poorly understood impact of icing on an airframe made weather seem like less of a danger than it really was. Since CVRs and data recorders were still far in the future, many weather-related accidents were unsolved.

Read the book "Fate Is The Hunter" by Ernie Gann, who was flying DC-2s and 3s for American. One of the all time great aviation books.
In the 30s, they just blundered right through thunderstorms if they couldn't be visually avoided because they were embedded in cloud or it was at night, and hung on for dear life.


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Where to find general A320 E&E Compartment Information?
I'm student in electrical engineering and write my thesis on some topic of the e&e compartment. The main focus is on the computers of the A320 flightcraft, actually called E&E Compartment. Sadly because of closed source of this avionics part there is no general information of what it is. This is also clear why, most infos can only accessed by technician because of several security reasons. But maybe there is still some general descriptions and pictures that shows for example the location of e&e and text like: e&e has distributed system architecture where each computer has specific role, they are all connected by arinc... blabla.. and similiar and so on :)
It can be all, books, patents, googling keywords.. It would all help!
Thank you!

The term E&E is used only in Boeings aircraft. For Airbus try to Google "avionics compartment" as this is the correct term.
This specific data you Will find in wiring diagram manual and schematic diagram manual, sadly due the complexity of the systems you won't find only one file for all systems.

You mentioned that there is only one file for all systems. Do you have something specific? Is it possible to share at least the name of the document?

After good amount of search, I have found that the ATA 100 Link documents of A320 explain pretty well each system of a flight craft. This is a standardised set of docs that help organise data for MRO's and pilots.
The only problem is that most documents are somewhere in MRO companies. But several documents were nevertheless uploaded by some guys. If you search in google for example "A320 ATA 31" (and varying similiar) than you get different "book stores" where people around the world upload partly or fully this documents. Dates of this docs can vary from 1990 to 2018.
One example would be the A320 ATA 31 Indicating/Recording Systems, that describes very detailed PFD, ND, DMC, SDAC, ECAM and all other "cockpit" systems. Here the link.
My original question was more generally, but this docs helped me to understand a lot about this aircraft.